Reflecting a broadening interest in finding new ways to talk about contemporary social complexity, the concept of ‘super-diversity’ has received considerable attention since it was introduced in this journal in 2007. Many utilizing the term have referred only to ‘more ethnicities’ rather than to the term's fuller, original intention of recognizing multidimensional shifts in migration patterns. These entail a worldwide diversification of migration channels, differentiations of legal statuses, diverging patterns of gender and age, and variance in migrants' human capital. In this special issue of Ethnic and Racial Studies, the concept is subject to two modes of comparison: (1) side-by-side studies contrasting different places and emergent conditions of super-diversity; and (2) juxtaposed arguments that have differentially found use in utilizing or criticizing super-diversity descriptively, methodologically or with reference to policy and public practice. The contributions discuss super-diversity and its implications in nine cities located in eight countries and four continents.